I remember somebody mentioning this problem in another Profitec 700 thread. No reason or solution was mentioned at the time. Anyway, I have the same sound coming from the group when the basket reaches full pressure(9bar). In the other thread it was described as a dolphin call sound and that is exactly how it sounds like. The sound lasts between 1 and 2 seconds and happens 8 out of 10 times now. It happens with coffee in the basket and with the backflush disk. I have had this issue since the machine was new a few months ago, but it has gotten more frequent as time has passed.

Did any of the Profitec 700 owners find a cause/solution to this?

A video might be helpful but I think you're describing the sound as one of the seals engages as the system pressurizes. It's always worse after a chemical backflush and then after 20-30 shots it mostly goes away. It's just a lube issue and coffee oils are usually enough to make it go away.

It had this sound from the moment I got it. I guess Profitec went cheap on the lube at the factory. I'll put some lube on the valves over the weekend and report back.

It turned out to be lube or lack thereof. I unscrewed the mushroom and put a tiny bit of lube on the brew valve tip only. It's been a week and about 20 shots later no chirping sound.

Thanks for the followup! Greatly appreciated!

There's nothing more aggravating than a thread discussing a problem that goes dead (assuming this occurs after the OP fixed the problem) but then never checks back in with what the solution was or if it the problem was ever resolved.

Agree fully. I guess some problems just don't get solved though.